Snow in winter is the “enemy” of traffic. In the 1940s and 1950s, with the rapid development of transportation, snow-melting agents came into being. Snow-melting agents are mainly used in airports, highways, railways, urban streets and other places to remove snow or prevent freezing.
Chlorine salt snow-melting agents have been widely used in road snow removal and ice melting because of their good snow-melting effect and low price. Until now, some countries still use chlorine salts as the main components of snow melting agents, and China is no exception. However, excessive use of chlorine salt snow-melting agents leads to a large number of damage to roadside vegetation, and corrosion of roads, bridges and concrete roads, the snow mixed with chlorine salt snow-melting agents melt and then infiltrate into the surface, and contaminate rivers and groundwater, causing serious damage to the ecological environment. Therefore, it is imperative to study new types of snow-melting agents and improve the performance of existing snow-melting agents.
In the late 1980s and early 90s, the study of acetate snow-melting agents were started abroad, and the appearance of calcium magnesium acetate has made a breakthrough in the acetate snow-melting agents. The calcium magnesium acetate (CMA) is a mixture of calcium acetate and magnesium acetate, an environment friendly chemical developed in the United States in the 1980s as an alternative to the snow or ice removal agent sodium chloride in the freeway. Compared with sodium chloride, CMA has the advantages of low melting point, biodegradability, less corrosion to concrete and metal in highway infrastructure, and basically no pollution to soil and water sources. Usually, CMA is produced by the reaction of glacial acetic acid with dolomite, but this method has high production cost, and the price of CMA is 30 times higher than that of sodium chloride, which restricts the common application of CMA.
Brine purification process is a key process in salt industry to improve the purity of refined salt products, reduce the impurity content in salt and improve the whiteness of salt products. The chemical composition of the salt mud produced by the two-alkali brine purification process includes CaCO3, Mg(OH)2, and a small amount of NaCl and CaSO4, etc. Due to the large output and complex composition, direct emissions will cause environmental pollution. At present, most domestic enterprises treat salt mud as landfill waste. At present, the research and development of reasonable salt mud treatment industrial application technology is a technical problem faced by all salt making enterprises in China.